TimeControl for WMS-T layers

Description

I have implemented a simple slider for controlling the time in WMS-T layers. It is basically a horizontal slider (images copied from the ZoomBar) which allows for graphical change of the time in a WMS-T layer. I've also added a new sample, showing the new control.

I haven't done any unit tests yet. If the topic is of interest (I haven't seen a large amount of requests for WMS-T support), I'm happy do improve the control and add unit tests.